Winter Update 2015/2016
Greetings from the Windward woods!
Now that the fall rains have brought the end of the outdoor season for Windward, it's time to move inside close to the fire and get caught up on correspondence and documentation. Your support has allowed notable work to go forward this quarter, especially as regards to B2M's ability to generate the electricity it needs to run the control computers, sensors, solenoid valves, etc., and beyond that, to provide electricity for the village.
That's where an Axial-Flux Alternator (AFA) comes into our adventure.
Central to the vision of Biomass to Methanol is the recognition that no one form of energy will meet all of a village's needs; replacements will be needed for the full range of fossil-fuel based energy forms such as diesel, gasoline, natural gas and coal-generated electricity. With your help, we've already been able to demonstrate our ability to convert woody biomass into a replacement for natural gas (aka wood gas), and we've demonstrated our ability to use wood gas to power various types of gen-sets. Here's a quick video of our Opalyn using the gasifier she built to power a low-rpm engine driving a standard alternator. The light you see in the video is being produced from wood chips, and that's Opalyn in the leather welding jacket at 0:10 in the video doing the conversion.
Most first world countries burn coal to generate electricity. Using woody biomass to generate electricity is currently the sort of arrangement you would find in rural India as a way to convert locally produced biomass into electricity to light the village at night. Here's a short video that describes the problem from one rural farmer's perspective. A key long-term B2M goal is to help improve these sorts of systems.
While we've established that we have the ability to burn wood gas in a gen-set and produce electricity, one problem with going that route is that two thirds of the energy in the biomass come out as the hot exhaust of the internal combustion engine. As a result, one of B2M's key goals is to incorporate ways to capture a significant portion of that waste heat and convert it into electricity. One way we anticipate doing that is by using a flash-boiler to generate steam from the hot exhaust of the internal combustion engine that drives the hydraulic pump that lies at the heart of the biomass compressor.
Axial Flux Alternators
Then we'll use that steam to power a steam engine that will spin an Axial Flux Alternator. Here's a video in which you can see a small steam engine driving an AFA; the steam engine is turning two magnetic disks, one on each side of the stator. The "stator" is the stationary disk in the video; it contains a series of copper coils embedded in fiberglass. Electricity is generated as the magnets spin past the stator's coils; more about stators a bit further into our tale.
An AFA is very different from the alternator in your car. Those are designed to turn at around 5,000 rpm, and consequently have to be manufactured to very close tolerances. An AFA is designed to run at one tenth that speed, and the way the math works out, reducing the speed by a factor of ten reduces the internal stress by a factor of a hundred. As a general rule, the slower the engine rpm, the longer the engine life.
The lower internal stress translates to this type of device being much easier to fabricate and maintain in a village setting. That's an important part of B2M because we're committed to creating an integrated system that can be primarily manufactured and maintained using village scale technology. The AFA's more forgiving design makes it our go-to method for generating electricity. Instead of the high precision bearings that an automobile alternator needs, an AFA can run on bearings made from the dense wood from our dry land oaks, and lubricated with sheep tallow.
The current surge of interest in AFAs stems from the desire of people to build home scale wind generators. The AFA's low design speed matches the ideal speed for a home-scale wind generator, and since that just happens to be the speed at which steam engines run, we're piggy-backing on that work.
This year, while Ruben was working on the Biomass Compressor's computer controls, and I was focused on constructing a walk-in cooler and the Digital Studio, Yoseph focused on the task of hooking up an AFA to our 1 horse-power steam engine. Once operational, AFA 1.0 should generate 700 watts of electricity. That may not sound like a lot, but it's actually a fifth of Windward's average, year-round electrical consumption. A key part of the work involved not just building a B2M spec'd AFA, but to do it in such a way that it can be integrated with the control computer that will be operating the larger system.
The author Robert Heinlein counseled that when faced with a system that is large and difficult to understand, tackle the parts of it you do understand, and whittle it down to size. As to B2M, we have a good idea of what all the various parts of the system are, but we have a long way to go before we will have mastered them all. We're very appreciative that Yoseph has taken on the challenge of sorting out this crucial part of the B2M system.
The stator is the stationary part of an axial flux generator. It consists of a series of copper coils that are configured to produce three-phase current when a magnet passes by them. If you're interested in the details, here's a video that shows how a stator is cast using fiberglass and resin.
Here's a pic of Yoseph showing off our latest stator. He's holding it up so that sunlight shines through to show the placement of the nine internal coils where the electricity is generated. This is the second stator we've cast for B2M, as we test out various options. Because the design specs for our application are different from a wind generator, we expect that we'll have to make up a series of stators using different wire sizes and number of turns in order to settle on the design that will optimize the conversion of thermal energy into mechanical energy into electricity.
This work is key to what makes B2M different from coal, oil or natural gas powered on-demand energy systems that convert one third of the input energy into electricity. B2M is designed to convert that "easy third" into liquid fuels, and then to go on to use a series of additional steps to use the "waste" energy to meet the village's electrical and residential heating needs. By operating as a village energy system, B2M can look to achieve energy utilization rates in the 90% range. That level of efficiency translates into much lower pressure on the village's forest to supply biomass, hence increased system sustainability.
Thank you again for your willingness to have faith in this project, and to help support the work. We couldn't do this without you.